Metal Matrix Structural Fuse for Fatigue-Resistant Shear Control
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Solution Overview
Problem
Structural fuse pins in aircraft experience fatigue cracks due to cyclic loading, leading to premature failure and increased weight when attempts are made to enhance their size to reduce fatigue, resulting in excessive weight addition to the aircraft.
Innovation Solution
A structural fuse comprising a metal matrix composite with elongate reinforcing elements, such as ceramic fibers, arranged in specific orientations and configurations within a metal matrix, including hollow metal ceramic spheres, to enhance fatigue properties and control the shearing load range without increasing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the size of the fuse pin is increased to reduce fatigue failures, then fatigue resistance is improved, but weight increases considerably
Solution Approach 1:
The patent applies composite materials by embedding reinforcing elements (such as ceramic fibres, carbon fibres, or other rigid/elastic materials) within the metal matrix of the fuse pin. This composite structure provides enhanced fatigue resistance and mechanical strength without proportionally increasing the overall weight, as the reinforcing elements are distributed throughout the matrix rather than requiring a uniform increase in pin dimensions. The composite architecture allows for optimized weight-strength ratio.
Solution Approach 2:
The patent implements local quality by strategically positioning and orienting reinforcing elements within specific regions of the fuse pin's metal matrix. The reinforcing elements can be arranged in particular orientations (e.g., axial, radial, or helical patterns) to address fatigue stress concentrations at critical locations. This localized reinforcement provides targeted fatigue resistance where needed most, rather than uniformly strengthening the entire pin, thereby minimizing unnecessary weight addition.
2Duration of action of stationary object
If the size of the fuse pin is increased to prevent fatigue failure, then operational life is extended, but the components attached to the pin must be strengthened accordingly, resulting in excess weight
Solution Approach 1:
By incorporating reinforcing elements into the metal matrix, the fuse pin achieves extended operational life through improved fatigue resistance without requiring a proportional increase in overall pin size. The composite structure provides enhanced durability while maintaining a compact form factor, thereby avoiding the need to strengthen attached components and preventing the snowball effect of excess weight addition throughout the aircraft structure.
Solution Approach 2:
The strategic local reinforcement of the fuse pin through embedded elements extends operational life by addressing fatigue at critical stress points without requiring a uniform increase in pin dimensions. This localized approach to enhancing durability ensures that attached components do not need to be strengthened, thereby preventing the propagation of excess weight through the aircraft's structural hierarchy.
3Ease of manufacture
If conventional metal fuse pins are used, then manufacturing is simple, but fatigue cracks develop due to cyclic loading
Solution Approach 1:
The patent employs composite materials by integrating reinforcing elements into the metal matrix of the fuse pin. This composite construction significantly improves fatigue resistance and reliability under cyclic loading conditions. While the manufacturing process becomes somewhat more complex compared to conventional metal pins, the enhancement in reliability and operational life far outweighs the additional manufacturing complexity, particularly in safety-critical aircraft applications.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a structural fuse with improved fatigue resistance and extended operational life, allowing for a narrower load range control and reduced weight, thereby preventing damage to aircraft components without adding excess weight or compromising strength.
Implementation Method 1
at least a portion of the metal matrix may comprise a plurality of hollow metal ceramic spheres. This results in a foam-like material that can absorb higher loads than a solid metal fuse.
Implementation Method 2
The provision of such a so-called metal matrix composite results in a fuse having improved fatigue properties and hence a longer operating life.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A structural fuse 1 is configured to shear upon an application of a predetermined load and comprises a plurality of elongate reinforcing elements 4 in a metal matrix 5. The provision of a so-called metal matrix composite results in a fuse that is lighter in weight than a conventional metal pin and has improved fatigue properties and hence a longer operating life. The load (or range of loads) at which the fuse is arranged to shear can be engineered by careful arrangement of the orientation of the reinforcing elements, and by selecting the proportion of reinforcing elements in the matrix. Thus, a fuse having a narrower load range than hitherto achievable can be produced.